The Future on Display

"All of these methods, whether it's Gyricon spheres or electrophoretic particles, you want them to be bistable, but not too bistable, and you don't want them to relax too quickly," says Dave Biegelsen, a research fellow at PARC. "So the control of ions in liquids—whether electrophoretic or Gyricon—has always been a bit of a problem. It's only in these small increments over long periods of time that these things finally become stable technologies."

The initial interest in Gyricon was its potential as a reusable and portable electronic paper. Biegelsen says researchers found early success with watches, calculators, and other products designed with large, seven-segment displays—though the intent was to boost the resolution. Gyricon media was made in a continuous-roll process in 2-ft-wide swaths, but Street says there was no obvious technical limit to making it bigger than that. "That made the signage part of it very attractive. You could boost the media very well," he notes.

In the beginning, Gyricon relied on voltage delivered via a fixed path of electrodes, a setup that Street says allowed users to make a limited number of fonts and characters. "Then the technology moved into essentially an arbitrary addressing of each pixel in the backplane—an active-matrix backplane. That allowed a more versatile, more complete set of images that could be displayed," he explains.

Another development was a process in which each bichromal ball was encapsulated in its own external, transparent sphere and held in a liquid, much like an egg sac. "You could, in principle, print those," Biegelsen says. "So you could have Gyricon ink if you wanted."

The Gyricon company incorporated about six years ago and took the lead on technical development. Some of that technology remains at PARC, but most was transferred to Gyricon LLC. Xerox Corp. terminated the operations of Gyricon LLC, its wholly owned subsidiary, at the end of 2005 and has since focused on licensing the intellectual property associated with its electronic paper. Re-imagable paper remains a part of ongoing projects at Xerox.

Electronic-ink displays

Research started at the MIT Media Lab led to the foundation of Cambridge, MA-based E Ink Corp. in 1997. E Ink's electronic-paper displays rely on microcapsules. Each microcapsule contains clear fluid, positively charged white pigment chips, and negatively charged black pigment chips. The electrical field you apply determines which pigment chips rise or fall. The microcapsules are smaller than 50 microns in size.